Bump lxml from 4.6.3 to 4.9.2 (#2212)

Bumps [lxml](https://github.com/lxml/lxml) from 4.6.3 to 4.9.2.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.6.3...lxml-4.9.2)

---
updated-dependencies:
- dependency-name: lxml
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

base-requirements.txt

@@ -13,7 +13,7 @@ psycopg2-binary==2.8.6
 python3-openid==3.2.0
 python-decouple==3.4
 # lxml used by BeautifulSoup.
-lxml==4.6.3
+lxml==4.9.2
 cssselect==1.1.0
 feedparser==6.0.8
 beautifulsoup4==4.11.2